Professional IronPython

using Late Binding
When using late binding, you create a connection to the COM component at run time by creating
a new object or reusing a running object. Some developers prefer this kind of access because it’s less 
error prone than early binding where you might not know about runtime issues during design time. 
Here are some other reasons that you might use late binding.
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More connectivity options: You can use late binding to create a connection to a new instance 
of a COM component (see the “Performing Late Binding Using Activator.CreateInstance()” 
section of this chapter) or a running instance of the COM component (see the “Performing 
Late Binding Using Marshal.GetActiveObject()” section of the chapter).
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Fewer modules: When you use late binding, you don’t need an interop assembly for each 
of the COM components you want to use, which decreases the size and complexity of your 
application.
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Better version independence: Late binding relies on registry entries to make the connection. 
Consequently, when Windows looks up the string you use to specify the application, it looks 
for any application that satisfies that string. If you specify the Microsoft Excel 9.0 Object 
Library COM component (Office 2000 specific), Windows will substitute any newer version 
of Office on the system for the component you requested.
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Fewer potential compatibility issues: Some environments don’t work well with interop assem-
blies. For example, you might be using IronPython within a Web-based application. In this 
case, the client machine would already have to have the interop assembly, too, and it prob-
ably doesn’t. In this case, using late binding allows your application to continue working 
when early binding would fail.
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